Paranasal sinus X-ray abnormalities commonly occur in asthmatics; however, the significance of these findings is unknown. Anecdotal evidence suggests that sinusitis may be a trigger for asthma. The long-term goal of this project is to characterize the upper respiratory tract inflammation of sinusitis and rhinitis in asthmatic children and to determine the effect of this inflammation on the course of asthma and bronchial reactivity. Using both a clinical and a laboratory approach, mechanism of supper respiratory tract inflammation on airways function and bronchial reactivity will be investigated. Clinical studies will characterize the asthmatic child with chronic sinusitis by clinical signs and symptoms, laboratory data, and nasal and sinus cytology and histology. Children at risk for bacterial or viral infection will be identified. The effect of upper respiratory tract inflammation on course of asthma and bronchial reactivity will be determined in a 3-week double-blind, placebo-controlled trial. In a 6-month double-blind, placebo-controlled trail, the effect of prophylaxis of upper respiratory tract inflammation on course of asthma will be evaluated. To investigate mechanisms of the effect of upper respiratory tract inflammation on airways function and bronchial reactivity, and animal model with sinusitis induced by the chemotactic peptide C5a des Arg has been developed. Pulmonary functions and histamine dose-response relationships will be determined in these rabbits with sinusitis. Effects of "post-nasal drip" and breathing cold air will be determined in this model. The possibility that mediator release from a distal inflammatory site may alter or affect airways function and bronchial reactivity will be determined to validate the uniqueness of upper respiratory tract inflammation. These studies will be valuable clinically in determining the importance of upper respiratory tract inflammation on course of asthma and bronchial reactivity, and in elucidating the mechanisms of this phenomenon.